The present disclosure relates to a method of manufacturing a flash memory device.
A flash memory device is a nonvolatile memory device that does not lose data stored therein even if power is turned off In addition, flash memory can record, read, and delete data at a relatively high speed.
Accordingly, flash memory devices are widely used for the Bios of a personal computer (PC), a set-top box, a printer, and a network server in order to store data. Recently, flash memory devices are extensively used for digital cameras and portable phones.
In such a flash memory device, a semiconductor device having a SONOS (Silicon-Oxide-Nitride-Oxide-Silicon) structure is mainly used.
Different from a flash memory device having a floating gate including polycrystalline silicon, the SONOS memory device is a charge-trap type device, in which gate voltage is applied to charges in order for the charges to pass through a thin oxide layer formed on silicon, so that the charges are injected into or released from a trap formed in a silicon nitride layer.